Watch for moon's spectacular triple play Wednesday

Published January 29. 2018 1:18PM

Mark C. Borton

Imagine being 62.5 percent taller. You might or might not like that idea, but by any measure you would be a big deal.

Wednesday is going to be a big deal. On that day, something weird and wonderful is going to happen. The heavens are going to align in just the right way, and we are in for a sky-watching treat. Keep your fingers crossed that the clouds will come some other day, for you will want to see the fullness of the moon in all its glory.

On the 31st the moon will perform a hat trick, a trifecta: a “super moon,” a “blue moon,” and a “blood moon” — all at once. It is what astronomers call a syzygy. What does that mean?

1: The moon’s orbit around the Earth is elliptical: it’s not a perfect circle, but oblong, and thus at various distances from the Earth. When it is far away, at apogee, it appears (to us to be) smaller and darker. At perigee, like on Wednesday, it will be 30,000 miles closer and appear (to us) as a “super moon” – 14 percent larger and 30 percent brighter. This effect is most pronounced when the moon is close to the horizon and juxtaposed against something familiar, like a church steeple.

Moonrise in New London on Wednesday is 5:27 PM, in the east-north-east.

2: A “blue moon” occurs when you have either 13 full moons in a year, or two full moons in the same month. We had a full moon on January 1 and will have a second full moon on January 31. Blue moons are rare, occurring on average once every 13 or 30 months, depending on your chosen definition.

3: A “blood moon” refers to the dark reddish color of the moon during a lunar eclipse. A lunar eclipse occurs when the Sun—Earth—Moon are aligned, in what’s called syzygy, causing the Earth to partially or fully block the light of the Sun from falling on the Moon. The Earth’s atmosphere also bends some of the Sun’s light like a prism, with the reddish part of the spectrum falling on the moon, giving it a reddish color.

Wednesday will be a total lunar eclipse, but only partially visible from the East Coast. You will need to be up early in the morning to see the show, since the eclipse begins at 5:51 a.m. in New London, and reaches its maximum at 6:54 a.m. You will want to be up somewhere high with an unobstructed view to the northwest. For those of us on the East Coast, the show’s over when the moon drops below the horizon at 6:58 a.m.

To see the total eclipse, you would need to be further west — say Hawaii.

The special effects of the moon’s trifecta are not limited to the sky: the sea will respond with a standing ovation called “spring tides.”

In New London, our daily tide range, the difference between high tide and low tide, is usually 2.6 feet. At the full and new moon, we get higher than normal tides, called spring tides. But on super-moon day, when the moon is close to apogee, the tides will respond to the gravitational pull of the moon like a raw recruit to a drill sergeant: they will jump higher. They will jump to about 4.15 feet, an increase of 62.5 percent. So prepare for some minor coastal flooding.

In Canada’s shallow Bay of Fundy, between New Brunswick and Nova Scotia, the ocean tide has to go a long way across the Grand Banks before funneling into the Bay. This tends to squeeze the tides from a wide area into a small area. Since you can’t compress water, all that water has to go somewhere — so it goes up.

The normal tide range at Minas Basin at the far end of the Bay of Fundy is about 30 feet. But because of the syzygy at the end of January, the height of the tide is predicted to reach a near-record 51.77 feet. You can be sure that the Canadians are preparing for some serious coastal flooding.

On the first blue moon in January, some Boston suburbs had icebergs floating down their streets. During the “Blizzard of 1978,” a fierce on-shore winds combined with a syzygy to create a storm surge or “storm tide” with exceptionally high tides and waves that wreaked havoc on the New England Coast.